1. Field of the Invention
The present invention relates to a wire insulating line. Particularly, the present invention relates to a cooling device for cooling down a traveling high-temperature coated wire in a cooling water tank and a cooling mechanism provided between the cooling tank and a take-up machine.
2. Background Art
A wire insulating line is designed to apply resin coating on a core wire while making the core wire to travel, cool down the resin-coated and traveling high-temperature coated wire, and take up the cooled-down coated wire. Such a wire insulating line is provided with a cooling device for cooling down the traveling high-temperature coated wire after resin application in order to set the resin coating, which has been applied by an extruder, by cooling (coagulation fixing, cooling solidification).
Conventionally, the cooling device for coated wire is generally constituted such that the high-temperature coated wire after resin application by the extruder is cooled down by being allowed to soak and travel in cooling water of a cooling water tank (reservoir tank) that extends horizontally. Note that the temperature of the resin coating after resin application by the extruder is generally 150 to 300° C., and is about 180° C. when the resin coating is PVC (polyvinyl chloride), for example.
However, since the conventional cooling device for coated wire, which is constituted by the cooling water tank (reservoir tank), simply allows the high-temperature coated wire to travel in the cooling water of the cooling water tank, it has had disadvantages that cooling speed to the coated wire was slow, a long cooling water tank where a traveling distance of the coated wire could be secured was necessary, and a large installing space was required.
Further, a coated wire haul-off machine is another constituent element of the wire insulating line. The coated wire haul-off machine is provided between the cooling water tank and the take-up machine in the wire insulating line, hauls-off the coated wire sent from the cooling water tank to allow it to travel, and also cools down the coated wire in the cooling water. FIG. 17 is a schematic block diagram showing an example of a conventional coated wire haul-off machine. As shown in FIG. 17, a conventional coated wire haul-off machine 58 includes front and rear capstans 60, 61 for winding a coated wire 56 by allowing it to reciprocate back and forth for several times in a casing 59 and a plurality of shower nozzles 62 that spray the cooling water to the coated wire 56 traveling between the front and rear capstans 60, 61, in the casing 59 where the traveling line of the coated wire 56 is arranged to pass inside thereof. Note that the lower stream (right side in FIG. 17) of the same traveling direction of the coated wire in a coated wire manufacturing line is defined as front and the upper stream (left side in FIG. 17) of the direction is defined as rear, in this specification.
On the other hand, Japanese Patent Laid-Open No.Hei6-338231 publication discloses a wire cooling apparatus that cools down a resin coated layer of a coated wire that has been cooled down in a cooling water tank in a state where the wire is wound on an accumulator. FIG. 18 is a schematic block diagram showing the constitution of a wire cooling apparatus according to prior art.
The wire cooling apparatus is arranged between the cooling water tank and the take-up machine (more specifically, between the haul-off machine and the take-up machine in the lower stream of the cooling water tank) as shown in FIG. 18, and includes an accumulator 72 that comprises front and rear turn sheaves 72A, 72B for absorbing a speed difference between the haul-off speed of a coated wire 71 and the take-up speed of the take-up machine, a cooling tray 73 that is arranged under the accumulator 72 while reserving the cooling water and cools down the coated wire 71 accumulated around the accumulator 72 by allowing the wire to travel in the cooling water, and a tension additional mechanism (not shown) that moves the front turn sheave 72A in the arrow 74 directions to absorb speed fluctuation of the coated wire 71.
As described, the cooling tray 73 is arranged under the accumulator 72, a part of the front and rear turn sheaves 72A, 72B sinks in the cooling water of the box-shaped cooling tray 73 whose upper portion is opened, the coated wire 71 traveling on a lower coated wire traveling path between the front and rear turn sheaves 72A, 72B sinks deeply, and thus the coated wire 71 accumulated around the accumulator 72 is cooled down.
However, since the above-described coated wire haul-off machine 58 including the shower nozzles 62 is designed to spray the cooling water in a shower state to the coated wire 56 traveling between the front and rear capstans 60, 61, it has lower cooling capability than the one allowing wires to travel in the cooling water, and there are cases where the coated wire 56 is not sufficiently cooled down to a predetermined temperature when wire speed is increased and a part of its resin coating is crushed when the wire is taken up by the take-up machine in the lower stream to cause shape deformation.
Then, to cool down the coated wire in the coated wire haul-off machine, applying the above-described cooling tray 73 of the wire cooling device to the coated wire haul-off machine instead of the shower nozzles 62 is considered.
However, in the case of the coated wire haul-off machine including the cooling tray, a part of each of the front and rear turn sheaves 72A, 72B (hereinafter referred to as capstans) sinks in the cooling water in the box-shaped cooling tray whose upper portion is opened, and the coated wire traveling on the lower coated wire traveling path between the front and rear capstans travels in the cooling water at a certain depth. For this reason, stress (tensile stress) applied to the coated wire when the wire is pulled to travel against resistance applied to the coated wire due to contact with the cooling water, that is, stress (tensile stress) applied to the coated wire caused by the contact with the cooling water becomes large. Further, since a part of each of the front and rear capstans sinks in the cooling water, the cooling water hinders rotation of the capstans and the coated wire is pulled to travel against the water, so that the stress applied to the coated wire further increases.
Consequently, in the case where the cooling tray is provided in the coated wire haul-off machine instead of the shower nozzles, although such a machine has higher cooling capability than the one provided with the shower nozzles, it has larger stress applied to the coated wire, which is caused by the contact with the cooling water, and adherent force between resin coating and the core wire could be reduced due to stretch of the coated wire by the stress.